As known, intubation is defined as the introduction of a plastic tube called endotracheal tube into the trachea in order to ventilate a patient. One of the main problems in performing this procedure, is the location of the tube within the trochea and not the esophagus. A wrong intubation within the esophagus, means death because of hypoxia. The old methods for ensuring the proper location of the endotracheal tube, consist in auscultation over the stomach, which should reveal characteristic sounds if the tube is in the esophagus. However, transmission of sounds to the lungs created by ventilation through an esophageal intubation may result in a false feeling of security. Furthermore, there are certain circumstances, particularly in battle field injuries and road accidents where the multiple trauma precludes abdominal auscultation. In a very recent paper (Anesthesiology, 59, p.344-6, 1983) the detection of endotracheal tube accidents by monitoring carbon dioxide concentration in respiratory gas was mentioned. Based on this approach, it was suggested (Anesthesiology, 60, 613-4) the use of the Einstein carbon dioxide detector based on the chemical attributes of cresol red and phenophthalein indicators which change colors in the presence of an increased concentration of hydrogen ions resulting from the carbonic acid obtained from the carbon dioxide in the respiratory gas. The indicators are used in the form of a solution of 3 mls of phenophthalein and 3 mls cresol present in a chamber through which the catheter end of the mucus trap is introduced. Although the clinical application of the Einstein device, is mentioned by the authors to be simple, it has the main disadvantage in the poor reliability of the correct location. This is a consequence of the inaccurate result from the change in the indicator colour, in view of the low acidity level imparted by the carbonic acid. It has also been stated (Anesthesiology, 61:782, 1984) that the device described above "is awkward, messy and dependent on prior preparation". In this communication it is suggested to utilize an expensive electronic carbon dioxide detector device. The device aspirates gas thhrough a fine plastic capillary that can be attached to the elbow connector of the anesthesia breathing circuit. However, such devices are impractical in every day use, because they need electric power supply, are difficult to operate and can not be consumed by underdeveloped countries.